In a distributed control type network having a plurality of nodes, each node has a clock generator. These nodes manage a cycle of data communication based on the clocks generated by the respective clock generator. However the frequency of each clock generator (clock frequency) has a subtle error. Therefore each node performs data communication while synchronizing with other nodes, so that the communication cycles do not deviate due to an error of the clock frequency. The distributed control method is also used for the FlexRay protocol, which is suitable for increasing the speed of an on-vehicle LAN (Local Area Network). (For example, refer to Japanese Laid-Open Patent Publication Nos. 9-46762 and 2008-294656, and FlexRay Communications System Protocol Specification Version 2.1, Chapter 9, 2005.)